Lever vang

[woodspars]

I am in the process of fitting out an old Laser hull. I am becoming increasingly annoyed with the high cost of running rigging, especially blocks. I an effort to control costs by reducing the number of blocks I will need, I have decided to use a lever vang. No such system currently exists for this type of boat, so I must design/build one.

Is anyone familiar with this sort of boom vang? I need to know the dimensions of the lever. Typically, this sort of system uses a triangular lever connected near the midpoint of a line that runs from the boom to where the mast meets the deck. This line is actually 2 lines: the upper part runs from the boom to a corner of the triangle, and the lower runs from the mast/deck to a corner of the triangle directly below the aforementioned corner. The remaining corner is at the end of the lever and typically has a 2 or 3:1 tackle attached to it.

A modern Laser vang is usually 16:1. How does one calculate the mechanical advantage of this sort of lever? How far apart should the upper and lower attachment points be placed? How long should the lever be? Any suggestions?

Thanks

-Tyler

[John E Hardiman]

Lever vangs have very specific applications (generally for crew clearence) and I don't think this is one. Also, I don't think you could build one (they are very highly loaded and need good design) for the cost of replacing the four 1/4" tackle blocks needed to get 16:1 or a "magic box".

[Tom Lathrop]

Racelite stainless hardware has been around forever and is reasonably inexpensive. The gadget you are talking about is called a Highfeld Lever and is fine for an outhaul but I don't think I'd want one for a vang where you want different levels of tension for different wind conditions.

I have made my own levers and it is not too difficult.

[paladin]

it dunno take much to make one...or two.....and if you drill a small series of holes you can control the force for various loading conditions...

[Boatmik]

For a few years in the early '80s lever vangs were all the rage.

Not hifield levers but simple aluminium levers. The big limitation is that to get 8 to 1 ...

You ended up with only a bit over an inch of adjustment and the other end of the 10 inch lever had to go through a huge 20" swing.

Thats why we all went to cascade systems using a total of 4 blocks.

That way they could take up the whole distance of the vang and divide it by 16 to get the full adjustment. Generally this allows 2 or three inches of adjustment for the total vang length.

Best wishes
Michael Storer

[Hwyl]

You could combine the lever with the existing blocks. There are lots of ways of using the original factory blocks with more purchase.

If you're not racing, the originals are fine anyway.

[woodspars]

Thanks to all for the advice.

I had been considering a combination of blocks and a lever - perhaps a 4:1 lever with a 3:1 purchase on the end. My main motivation is to save money.

For those of you familiar with the Laser, do you have any advice on the dimensions of a 4:1 lever? How does one calculate this sort of thing?

Thanks again.

-Tyler

[paladin]

make one...if it breaks...double the dimensions ....Arthur Piver..:D

[Boatmik]

The levers we were using were around 10" long.

And Arthur Piver designed heavy boats! Put it up less than double!

MIK!

[Tom Lathrop]

Having started sailing a Laser with 3 digits in 1971, I think you are complicating a simple boat. The original rigging was primitive and just a bit difficult to finesse, but that was part of the atraction.

[bainbridgeisland]

I have owned two sailing dinghies with vang levers made by Holt Allen. I have also owned a Midget Ocean Racer that had a lever vang. The system worked on all 3-boats.

Maybe you can educate me why you need so much power on a Laser vang. I have bent at least 3 bottom sections of Laser masts with the stock vang. Seems to me more power is not really needed. (I have talked to other Laser sailors about this. They seem to think it is needed but have not ever given me any reasonale technical justification. Seems like a gear war or style driven choice to me.)

Anyway, lever vangs are powerful and have limited throw just as others have mentioned. You could simply cut one out of aluminum plate if you wanted. But you would pay a weight penalty if it was strong enough. Plus, Idon't think you would save any money if you bought the Holt Allen lever compared to a block fall.

[Zane Lewis]

Back in the 80's a stock laser vang was a basic 4:1. This was adiquite for beach and fun sailing. However to get the best for racing people went and added a number of extra rope purchases because then extra blocks where not permited. Since then as you obviously know they have allowed the extra purchases.

Lever vangs are very common in NZ like you say just a length of alloy with holes drilled in it. mosly home made.

The only problem i can see with them on a laser is that due to the unstayed rig you have a lot more boom travel. In light the booms at normal height, in a blow the boom vang is on so tight the boom end is literally onto the rear deck.

So unless you are racing just go to the stock 4:1 and bounce your body weight onto the boom while pulling in on the rope. if you are racing the lever vang wiill be ilegal anyway.
Zane

[bainbridgeisland]

Hey Zane, Though I havent raced Lasers since the late 70s, the 4-1 vang seemed to work fine for racing too. So if it is powerfull enough to bend the mast, do you know why modern Laser sailors need more power? Our local Laser dealor could not answer this question. Nor could the Laser sailors I know.

[bamamick]

some of those old clamshell looking blocks Lasers used to come with. I don't see the need for a lever, but if you want I will measure everything on my Finn and give it to you next time I am at the yacht club.

I built a simple 4:1 vang for my last Windmill that would dump the top batten with no problem. You are talking about small extrusions. You don't want to tear your stuff up, especially if money is an issue.

jmo Mickey Lake

[Boatmik]

Hey Zane, Though I havent raced Lasers since the late 70s, the 4-1 vang seemed to work fine for racing too. So if it is powerfull enough to bend the mast, do you know why modern Laser sailors need more power? Our local Laser dealor could not answer this question. Nor could the Laser sailors I know.

It makes it a bit easier to adjust the sail around the course without coming too much out of hiking position.

With the old rig if you wanted to adjust the vang you had to move into the centre of the boat, pull fiercely on the vang while suddenly thrusting your weight down on the boom.

Now they can grab the end of the rope to pull it down.

MIK

[Zane Lewis]

Thanks MIK you got in before me. Thats exactly what we had to do. Even with the rope purchases you still some times had to come in. I have not sailed a Laser with the new 16:1 with blocks in it.
Anyway probably my last post for week. Have a 120 mile coast trip this week starting with 20-30knts from behind and looking like finishing with 30-40knts on the noise. Will take 2-4 days depending upon weather and where we can get shelter.
Zane

[woodspars]

Thanks to all for the posts.

I think the main motivation behind increasing power in the controls is to achieve ease (and perhaps accuracy) of adjustment. To me, 16:1 does seem a little excessive. I think this is a product of a mindset that considers more power to equal more speed. Multiple cascades of sparkling spectra lines certainly looks more "tech". When I raced these boats, I would keep an eye on these "tech" looking boats and would stick near them on the racecourse when I lacked tactics of my own. I can remember cursing the hopelessly underpowered controls on the Laser 2 and I'm convinced that these anachronistic controls led to the demise of the class. But, I digress.

I will try the lever vang, and I'll determine dimensions using a scale drawing of the system.

Thanks again.

-Tyler

[notwoodbut...]

I know that LASERs have changed the controls in last couple of years but what's wrong with the old way of pulling in the mainsheet all the way and then setting the vang and calling it a day? As far as line goes, you only need a few feet which you might be able turn up at your local boat yard for the cost of a little dumpster diving. A couple of blocks and you're good.
jim